Core Paper

ABSTRACT

A core paper comprising fiber material for producing a carrier material that can be laminated and that has at least one proportion of a reconstituted fiber material mixture and a wet sealer as a first additive, characterized in that the core paper comprises at least one active substance active on the boundary surface as a second additive for increasing capillarity at a weight proportion of 0.05% to 2% relative to the material.

The present invention relates to core paper, in particular to core paperas used for the production of decorative paper laminates. In addition,the invention relates to a method for producing the core paper and theuse of the core paper as a carrier material for and/or on the layerstructure(s) such as for example on boards of any kind

Core paper is known from prior art and is mostly used as a carrier fordecorative paper to produce laminates, which are often used, forexample, in the form of laminate boards and countertops, floor covering,etc.

The structure of such laminate consists of several interconnectedtwo-dimensional layers which are made from the same or differentmaterials in order to fulfill the specific functions and properties. Inthe production of decorative paper laminates, for example, core paper isused as one of these layers. Adhesive bonding of these layers is usuallyperformed by pretreatment of the individual layers, for example, byprior capillary impregnation and subsequently pressing the layers in thestack subject to temperature and pressure.

Core paper known to prior art is produced from a virgin fiber mix as itsraw material, which fulfills the demanding requirements for the requiredstrength, impregnating and paper properties.

In addition to the consumption of natural resources, the drawback ofusing virgin fiber mix inter alia is the high raw material costs.Reconstituted fiber material, however, such as recovered paper, oftendoes not satisfy the demanded requirements regarding strength,impregnation and paper properties.

The enormous cost pressure in today's paper industry leads to continuousproduction optimization and to the demand with respect to saving rawmaterial and transportation costs. This entails the trend towards lowgrammage, while demanding unchanged quality parameters such as unchangedstrengths, i.e. for lower grammage the requirements regarding strengthincrease accordingly.

With conventional impregnation methods, such as dip impregnation withimpregnating resins, the entire paper web is passed through the liquid.In order to not have any tears of the paper web in the production withthis method or any other disruptions of production, a certain wetstrength of the core paper web is a prerequisite. This wet strength isusually achieved by adding chemical additives, so-called wet sealers,where they should be optimally adapted to the chemistry in the system.

The object of the present invention is to at least partially overcomethe drawbacks known in prior art. The above object is satisfied by acore paper according to claim 1 according to the invention, a method forproducing the core paper, and the use of the core paper.

Particularly preferred embodiments are the subject matter of thedependent claims.

The present object is satisfied by the core paper according to theinvention containing the fiber material and possibly containingrecovered paper. The core paper according to the invention comprises atleast one proportion of a reconstituted fiber material mixture and a wetsealer as a first additive. The core paper according to the invention ischaracterized by adding at least one active substance active on theboundary surface as a second additive for increasing capillarity. Theadded amount of the second additive is in the range of 0.05% to 2%relative to the atro material.

According to the present invention, the core paper according to theinvention is understood to be carrier paper as it is used for example inlaminating decorative paper. In manufacturing this paper fromreconstituted, so called recycled fiber material, at least one substanceactive on the boundary surface is used in addition to conventional wetsealers.

Laminable within the meaning of the present invention is understood,according to the Latin root word “lamina” meaning layer, as being allkinds of binding of various material layers. The term carrier materialrefers to the layers of material on which or under which one (or more)additional layer (s) can be laminated. Laminates are often referred toas layer composites.

Reconstituted fiber material according to the present invention isunderstood to be all kinds of fiber materials that is reconstituted forthe production of paper, paperboard and cardboard, in particular of corepaper and used in particular for the production of paper, paperboard andcardboard in particular of the core paper. These kinds of recoveredpaper are in particular specified according to the CEN European StandardEN 643.

Wet sealers within the meaning of the present invention are understoodto be all additives which increase the strength of paper, paperboard andcardboard and core paper, inter alia in the wet state. In addition tothe mechanical interlocking of the fibers and the formation of hydrogenbonds during the sheet forming process, which are responsible for thestrength of the paper, wet strength agents connect inter alia the fibersat the points of contact and intersection. If the paper now becomesmoist or wet, by which the hydrogen bonds and hereby also the strengthis lost, then the wet strength agent maintains a part of the strength ofthe paper in the wet state. The wet strength is determined, for example,by means of a tensile load on a wet paper strip in a tensile testingmachine, which during constant feeding leads to a tear of the wet paperstrip. The use of wet strength agents is necessary in all areas ofapplication in which paper becomes wet or very moist, such as in thefield of hygiene or decorative paper. In the field of decorative paper,the wet strength is a prerequisite for the method step of resinimpregnation, in which the paper web is passed through a liquid bath.Many wet sealers or wet strength agents, respectively, must condense outand polymerize in the internal paper structure. This occurs only in partin the drying section of a paper machine. For complete formation of wetstrength, additional or curing time is usually necessary.

A substance active on the boundary surface according to the presentinvention is understood to be all kinds of substances that reduce thesurface or boundary surface tension between two phases. A boundarysurface is understood to be the surface between the two immisciblephases. A surface on the other hand is spoken of when one of the phasesis a gas, such as air. The phase boundaries can be characterized byboundary surface or surface tension describing the tendency to reducethe boundary surface. Depending on their chemical composition andapplication, substances active on the boundary are also referred to aswetting agents, detergents (surfactants, soaps) or emulsifiers. Suchmaterials are characterized by their polar structure in that the factthat they accumulate preferably at boundary surfaces of a dispersesystem. While “substance active on the boundary surface” refers to allsuch substances, the term “substance active on the surface” refers tosubstances that accumulate on the “surface” of a liquid at the boundaryto the gas phase, for example, at the surface of water, which can forinstance cause formation of foam.

Capillarity according the present invention refers to an effect whichoccurs as a result of the surface tension of liquids, preferably incavities. Basically the effect of capillarity is based of the molecularforces that occur within a substance (cohesion forces) and at theboundary surface between a liquid, a solid body (vessel wall) and a gas(e.g. air) (adhesion forces).

Based on capillarity is inter alia the capillary effect of sponges,wicks, cleaning rags, cloth and paper. The larger the inner surface (byvolume), the greater the capillary effect. The impregnating propertiesof the core paper according to the invention and the capillarityspecified in accordance with the present invention are influenced orcharacterized by the capillary behavior, the capillary rise, the liquidabsorption capacity, wetting, the edge angle, the surface tension.

Atro is the term for absolutely dry. Atro is also often referred to asotro (oven-dry). This term is the benchmark for measuring the drycontent of paper and pulp. The specification is, for example, accordingto the standard: BS EN ISO 638 Paper, cardboard and fibermaterial—Determination of dry content—Oven-drying process. Dosage ofadditives is commonly based on the dry substance.

In a further embodiment of the core paper according to the invention,the proportion of reconstituted fiber material mixture is greater than25%, furthermore, between greater than 40 and 100%, preferably between50 and 95%, particularly preferably between 70 and 90%, preferably inthe range of 75%, more preferably above 80%, most preferably above 95%and especially up to 100% and the fiber material is in particularselected from a group comprising for example Kraft pulp and/or Kraftliner in particular from department store waste from corrugated paperand cardboard with at least 70% corrugated paper and residues of solidcardboard and or packaging paper, used corrugated cardboard boxes,shreds of unused cardboard with layers of Kraft or test liner, usedcorrugated cardboard boxes with Kraft liner and/or corrugated medium onpulp and/or thermo-chemical pulp, used corrugated cardboard with layersof test or Kraft liner and at least one layer of Kraft liner, used bagsfrom Kraft pulp equipped as tear-resistant or non-tear-resistant, unusedbags of Kraft pulp equipped as tear-resistant or non-tear-resistant,used cardboard and paper from Kraft pulp naturally colored and/or white,shreds from unused pulp paperboard and paper from Kraft pulp uncolored,new carrier bags from Kraft pulp with or without wet tensile strengthresistant paper containing envelopes made of Kraft paper repeatedlycovered and/or coated and/or used, magazine paper, newspapers, inparticular daily newspapers, combinations thereof and the like.

The proportion of reconstituted fiber material relative to the totalfiber material is given as a percentage. Components of the total fibermaterial can also contain so-called virgin fiber material as well asartificial fiber material. In this, virgin fiber material, obtained bymeans of chemical and/or mechanical extraction processes, in contrast tothe reconstituted fiber material usually show higher strengths, but isalso more expensive.

Depending on the extraction process used, fiber material can basicallybe divided into fiber material containing lignin and free of lignin. Forreconstituted fiber material, this distinction is frequently no longergiven due to the mixing of recovered paper or even recovered papertypes, respectively. By means of strength parameters, static and dynamicstrengths can be distinguished. Static strength is understood to be theforce that a paper can withstand under a slow and steady tension load.For example, breaking force, tear length, tension length, modulus ofelasticity are among the static strength parameters. Dynamic strength isunderstood to be the force that can a paper can withstand under a fastand unsteady tension load. For example, specific tear growth resistance,burst strength, number of double folds (buckling strength) are among thedynamic strength parameters.

Examples of general paper properties are paper smoothness, porosity,roughness, permeability to air, formation, stiffness, flatness andopacity.

With the respective proportions of reconstituted fiber material, theproperties of the core paper according to the invention can inparticular also be influenced. The achievable strength parameters andwith respect to the impregnation method, the impregnation behavior ofthe core paper according to the invention, are of particular importantin connection with the trend to reduce grammage mentioned in theintroduction. The respectively necessary proportions of the overallfiber material are compiled according to the required strengths andproperties of the final product. A total fiber material from 100%reconstituted fiber material mixture requires optimized productionmethods and special technical know-how. Reconstituted fiber material canalso be referred to as recovered paper. Depending on properties andorigin, the CEN European Standard EN 643 lists the types of recoveredpaper in various classes. In particular types of waste paper from classII are of importance for the present invention.

In a further embodiment of the core paper according to the invention,the wet sealer is selected as the first additive from a group comprisingin particular compounds of epichlorohydrin resins, urea-,melamine-formaldehyde resins, phenol resins, acrylic resin dispersions,synthetic resin dispersions based on acrylic acid esters and/orstyrene-butadiene, polyurethane-, polyolefin dispersions, polyamidoamineresins, polyamidoamine-epichlorohydrin resins, combinations thereof andthe like. The mode of operation of these listed wet sealer groups inrelation to the connection of fibers at the points of contact andintersection was described above.

In a further embodiment of the core paper according to the invention,the substance active on the boundary surface is selected as the secondadditive from the group comprising compounds which, strongly accumulatein particular at the boundary surfaces. According to their functionalchemical groups, the additives are divided into bifunctional, anionic,nonionizable and cationic compounds. The characteristic feature of allthe substances active on the boundary surface is their polar structure,mostly due to at least one lipophilic hydrocarbon radical, and at leastone hydrophilic functional group, making them accumulate preferably atthe boundary surfaces of a disperse system.

Examples of substances active on the boundary surface, such assurfactants, are: amphiphilic (bifunctional) compounds with at least onehydrophobic and one hydrophilic part of the molecule, where ahydrocarbon chain comprises eight to twenty-two carbon atoms, (dimethyl)siloxane chains, perfluorinated hydrocarbon chains.

Examples of anionic surfactants are in particular soaps, linearalkylbenzene sulfonate, alkane sulfonates, alkyl sulfates, alkyl ethersulfates, fatty alkyl polyethylene glycol ether sulfates, fatty alkylsulfates.

Examples of nonionic surfactants are in particular fatty alkylpolyethylene glycol ether, fatty alcohol ethoxylates, fatty acidcondensates, ethylene oxide/propylene oxide copolymers (EO/PO), alkylphenol ethoxylates, sorbitan fatty acid ethers, sorbitan mono-(di, tri)laurate, -oleate, -palmitate, -stearate, polysorbates, sorbitansesquioleates, alkylpolyglucosides N-methylglucamides, alkylphenolpolyethylene glycol ethers, fatty alcohols, oxo-alcohols, Ziegleralcohols, alkyl phenols and ethylene oxide

Examples of cationic surfactants are in particular quaternary ammoniumcompounds containing hydrophobic groups, salts of long-chain primaryamines

Examples of amphoteric surfactants are, in particular betaine, aminoacid surfactants, N-(acylamidoalkyl) betaine, propylene oxide.

Further examples of anionic surfactants are polyelectrolytes,emulsifiers, wetting and dispersing agents, humectants, andpolysaccharides, in particular sorbitol.

In a further embodiment of the core paper according to the invention,the material suspension can comprise further additives which are addedin a controlled manner as so-called chemical expedients or additives inthe paper production process to achieve certain properties, effects, andprocess conditions, or are included already in a modified form in thereconstituted fiber material or recovered paper, respectively. This canbe, in particular retention agents, drainage aid agents, retentionagents dual systems or microparticle systems, wet and dry sealers,fillers and or pigments, in particular selected from a group of talc,titanium dioxide, aluminum hydroxide, bentonite, barium sulfate, calciumcarbonate, kaolin, gypsum, be binding agent components, color coatingcomponents, defoamers, deaerators, biocides, enzymes, bleaching aidagents, optical brighteners, dyes, shading dyes, fixatives,precipitating agents (fixing agents), wetting agents, pH regulatorscombinations thereof and the like. In addition to the desired functionsof the additives, interactions, however, can also result in adverseeffects, which then have the additives negatively influence the methodprocesses as so-called “trash”.

In a further embodiment of the core paper according to the invention,the active substance active on the boundary surface is added inparticular in a proportion of weight of 0.1% to 3%, preferably from 0.5%to 1 25%, more preferably from 0.1% to 1.5% and 0.5% to 1%,respectively, particularly preferably in the range of 0<x̂2% andpreferably from 1%, 1, 5% or 2% based on atro dry material. The dosagerange presently shown of the active substance active on the boundarysurface was determined from experiments and represents an optimizedactive range for obtaining the optimum paper properties, in particularfor increasing capillarity.

Core paper can be produced as follows: In a so-called stock preparationprocess, an aqueous fiber material suspension is provided. The fibermaterial suspension preferably has passed screening which includes inparticular a two-stage pressure screening and a 3-stage cleaner systemprocess, where the pressure screening preferably uses slotted screenerswhich comprise slots in particular having slot widths between 0.2 to 0.3mm and preferably 0.25 mm. Additional process steps can be dispersingstages and/or ash removal processes. In addition to other chemicalagents or additives, respectively, which influence the paper productionprocess as well as the paper properties, a wet strength agents and asubstance active on the boundary surface, a so-called surfactant, areadded to this fiber material suspension. The aqueous fiber materialsuspension, after the addition of all the raw materials/additives andjust prior to the paper machine, is also referred to as a so-calledfinished stock. With the paper machine process steps of drainage/sheetforming, pressing, drying, possibly smoothing and rolling-up, thebase-core paper is produced. After any possibly required ripening time,in which the final wet strength is achieved, the core paper is ready forthe method step of impregnation. In the method of capillaryimpregnation, the core paper is for example guided through an immersionbath and impregnated with resin.

In a further preferred embodiment, the passivation of carbonates, whichinter alia entered the core paper by the use of recovered paper, areprotected so that release of CO₂ is preferably prevented in the event ofshifts in pH-value. For example, carbonate content can be passivated bythe addition of small amounts of phosphoric acid. In addition, the fibermaterial can also be added suitable buffer systems in order to prevent apH shift.

Finally, a further aspect of the invention comprises the addition ofhydrophobic agents, thereby in particular influencing and adjusting thepenetration behavior of the core paper specifically by the addition oftwo oppositely-acting agents, i.e. especially between surfactants andhydrophobic agents.

Thereby, the addition of a hydrophobic agent leads to reducing the rateof wetting and can in particular dampend the wetting behavior possiblyabruptly caused by adding surfactants.

The object of the present invention is further also satisfied by amethod for producing a core paper according to claim 1. The method indetail comprises the following steps of:

-   -   providing a material suspension comprising at least one        proportion of a reconstituted fiber material mixture and a wet        sealer as a first additive, preferably from a stock preparation        process. This method step describes a basic requirement for the        (decorative/core) paper production process. Preferably, the        first additive is added in the stock preparation process, but        this can also be performed at least partly in the constant part.    -   adding an active substance active on the boundary surface as a        second additive in the finished stock suspension in the constant        part of a paper production process. The addition of the active        substance active on the boundary surface characterizes the        method according to the invention. Important for this method        step is optimal homogenization of the active substance active on        the boundary surface in the finished stock suspension, where an        addition of air into the system is to be avoided, which is        usually noticeable due to bubbles or foam forming    -   producing a core paper from said fiber material suspension on a        paper machine, in particular on a Fourdrinier wire, in        particular with a vibrating screen, and with or without a dandy        roll possibly with an attached hybrid former and a web guide        through a calender. This method step identifies some general        conditions of the production.

Furthermore, the above-described method according to the invention canalso comprise the additional step of

-   -   impregnating the core paper with a synthetic resin, wherein        impregnation is in particular resinification, saturation and/or        resin impregnation for the production of particle, in        particular, fiber composites. In particle and fiber composites,        particles or fibers are embedded in a different component of the        composite material, the so-called matrix.

Furthermore, the above-described method according to the invention canalso comprise the additional step of

-   -   forming a stack made of core paper using pressure and        temperature to produce laminated material. With this method        step, the use of the core paper for producing laminated material        is also claimed, in addition to the mere production of the core        paper according to the invention.

The present invention further comprises the use of the core paper as amaterial component in composite materials, in particular in laminatematerials, in particular compact boards (sometimes having a thickness ofup to 10 mm), fiber composites, and particle composites andinterpenetrating composites. This covers the use of the core paper forall geometries of the composite.

Furthermore, the present invention also comprises the use of the corepaper as carrier material for a web-shaped layer structure and inparticular for overlays, decorative paper, films and nonwoven materialsand/or as a cover layer, in particular as an overlay and pre-impregnatedpaper and/or as a carrier material on carrier boards in particular ofwood fiberboards, such as chip boards, oriented strand boards (OSB),fiberboards of high or medium density, plywood, mineral-bonded woodmaterials on a plastic base, solid wood panels, countertops, floorcovering, and preferably for the production of fiber compositematerials, such as natural fiber reinforced plastics, wood-plasticcomposites and fiber-ceramic composites, and/or in return thereof, inparticular as regenerated paper for coating back sides such as inparticular for laminates, surface-coated boards such as woodfiberboards, panels, and combinations thereof and the like. With theproduct examples listed, the core paper according to the inventioncovers the use as carrier material for all possible layer structures.

The main advantage of the core paper is that at least in partreconstituted fiber material is used, which allows saving costs for rawmaterials, increases the recycling rate and promotes the sustainable useof renewable resources.

Further advantages of the core paper according to the invention overprior art can inter alia be, that despite the use at least in part ofthe reconstituted fiber material, the demanding conditions regarding therequired strength, impregnation and paper properties are fulfilled,and/or are possibly even exceeded.

The invention is explained below with reference to preferredembodiments, where it is pointed out that these examples comprisemodifications or additions as they directly arise for the person skilledin the art. Furthermore, these preferred embodiments are no restrictionsof the invention such that modifications and additions are within thescope of the present invention.

For the production of core paper in prior art, grammage is used in therange from 40 to 400 g/m², preferably in the range between 140 to 300g/m², more preferably between 150 to 250 g/m², most preferably above 150g/m² uses conventional Kraft liner virgin fiber mix, in particular alsoKraft pulp. Ideally, the virgin fiber pulp comes from an upstream pulpproduction, so that there are no intermediate drying steps of the fibermaterial, so that there is in particular no hornification of the fibermaterial. Hornfication of the fiber material affects the surfaceproperties of the fibers and can negatively impact strength propertiesand the capillarity or absorbency of the finished core paper. Otherdifferences with respect to capillarity can be observed between fibermaterial containing lignin and not containing lignin. Fibers containinglignin unlike lignin-free fibers show reduced absorbency due tohydrophobic surface properties of fiber materials containing lignin.

In contrast to this, the production of the core paper according to theinvention is effected with up to 100% reconstituted fiber material.According to a preferred embodiment, waste paper types from unbleachedvirgin pulp were mainly used as reconstituted fiber material. Sheetformation of the core paper with a grammage between 40 to 400 g/m² takesplace at the paper machine, for example, in a single layer on aFourdrinier wire with an attached top wire drainage, in particular ahybrid former and/or a downstream dandy roll.

The quality criterion of the test series for the process steps in theproduction was the positive influence of capillarity of the core paper.

With the addition of an active substance active on the boundary surface,it was possible to achieved at least comparable capillarity for the corepaper according to the invention, which is inter alia apparent from asimilar capillary rise.

Simultaneously, it was possible to improve the wet strength, which isshown by an increase in tensile strength longitudinally (wet) in therange of 20% over prior art. Improved impregnatability is due toimproved wet strength of the core paper. A comparison is described belowin more detail with reference to values in the table.

Table 1 is a comparison of the reference parameters of the core paper.The paper parameters capillary rise, breaking force longitudinally(dry), tensile strength longitudinally (wet) and permeability to air arecompared with prior art. (100% virgin fiber/0% recovered paper), with100% recovered paper and with the core paper according to the invention.For the core paper according to the invention, the capillary rise andthe permeability to air are at the prior art level, the breaking forcelongitudinally (dry) reduced by half and the breaking forcelongitudinally (wet) is improved over prior art by 20%.

TABLE 1 Comparison of the compared parameters of the core paper. Papertype (material composition) Prior art 100% core paper (100% virginfiber/ recovered according to the Parameters: 0% recovered paper paperinvention Capillary rise 100% 40% 100% Breaking force 100% 70% 50%longitudinally dry Breaking force 100% 50% 120% longitudinally dryPermeability to air 100% 20% 100%

1. A core paper for producing a carrier material that can be laminatedcomprising: a fiber material according to the invention for producing acarrier material that can be laminated having a proportion of areconstituted fiber material mixture and a wet sealer as a firstadditive, a tenside as an active substance active on a boundary surface,and, a second additive at a proportion of weight of 0.05% to 3%,relative to atro dry material for increasing capillarity.
 2. The corepaper of claim 1 wherein the proportion of reconstituted fiber materialmixture is greater than 25%, between greater than 40% and 100%,preferably between 50% and 95%, particularly preferably between 70% and90%, preferably in the range of 75%, more preferably above 80%, mostpreferably above 95% and especially up to 100% and, the fiber materialis in particular selected from a group comprising for example Kraft pulpand/or Kraft liner in particular from department store waste ofcorrugated paper and cardboard with at least 70% corrugated paper andresidues of solid cardboard and or packaging paper, used corrugatedcardboard boxes, shreds of unused cardboard with layers of Kraft or testliner, used corrugated cardboard boxes with Kraft liner and/orcorrugated medium on pulp and/or thermo-chemical pulp, used corrugatedcardboard with layers of test or Kraft liner and at least one layer ofKraft liner, used bags from Kraft pulp equipped as tear-resistant ornon-tear-resistant, unused bags of Kraft pulp equipped as tear-resistantor non-tear-resistant, used cardboard and paper from Kraft pulpnaturally colored and/or white, shreds from unused pulp paperboard andpaper from Kraft pulp uncolored, new carrier bags from Kraft pulp withor without wet tensile strength resistant paper containing envelopesmade of Kraft paper repeatedly covered and/or coated and/or used,magazine paper, newspapers, in particular daily newspapers, combinationsthereof and the like.
 3. The core paper of claim 1 wherein said wetsealer is selected as the first additive from a group comprising inparticular compounds of epichlorohydrin resins, urea-,melamine-formaldehyde resins, phenol resins, acrylic resin dispersions,synthetic resin dispersions based on acrylic acid esters and/orstyrene-butadiene, polyurethane-, polyolefin dispersions, polyamidoamineresins, polyamidoamine-epichlorohydrin resins, combinations thereof andthe like.
 4. The core paper of claim 1 wherein said active substanceactive on the boundary surface is selected as the second additive fromthe group comprising compounds which, in particular, strongly accumulateat the boundary surfaces, comprising at least a lipophilic hydrocarbonradical, and at least one hydrophilic functional group, and inparticular surfactants, amphiphilic (bifunctional) compounds with atleast one hydrophobic and one hydrophilic part of the molecule, whereina hydrocarbon chain comprises eight to twenty-two carbon atoms,(dimethyl) siloxane chains, perfluorinated hydrocarbon chains, anionicsurfactants in particular soaps, linear alkyl benzene sulfonate, alkanesulfonates, alkyl sulfates, alkyl ether sulfates, fatty alkylpolyethylene, glycol ether sulfates, fatty alkyl sulfates, nonionicsurfactants, in particular fatty alkyl polyethylene glycol ether, fattyalcohol ethoxylates, fatty acid condensates, ethylene oxide/propyleneoxide copolymers (EO/PO), alkyl phenol ethoxylates, sorbitan fatty acidethers, sorbitan mono-(di, tri) laurate, -oleate, -palmitate, -stearate,polysorbates, sorbitan sesquioleates, alkyl polyglucosidesN-methylglucamides, alkyl phenol polyethylene glycol ethers, fattyalcohols, oxo-alcohols, Ziegler alcohols, alkyl phenols, ethylene oxide,cationic surfactants, in particular quaternary ammonium compoundscontaining hydrophobic groups, salts of long-chain primary amines,amphoteric surfactants, in particular betaine, amino acid surfactants,N-(acylamidoalkyl) betaine, propylene oxide, polyelectrolytes,emulsifiers, wetting and dispersing agents, humectants, andpolysaccharides, in particular sorbitol, combinations thereof and thelike.
 5. Core paper according to one of the preceding claims,characterized in that said material suspension comprises furtheradditives such as in particular retention agents, drainage aid agents,retention agents dual systems or microparticle systems, wet and drysealers, fillers and or pigments, selected in particular s from a groupof talc, titanium dioxide, aluminum hydroxide, bentonite, bariumsulfate, calcium carbonate, kaolin, gypsum, and binding agentcomponents, color coating components, defoamers, deaerators, biocides,enzymes, bleaching aid agents, optical brighteners, dyes, shading dyes,fixatives, precipitating agents (fixing agents), wetting agents, pHregulators combinations thereof and the like.
 6. The core paper of claim1 wherein said active substance active on the boundary surface is addedin particular in a proportion of weight of 0.1% to 3%, preferably from0.5% to 1.25%, more preferably from 0.2% to 0.75% and most preferablyfrom 0.25% to 0.5% based on atro dry material.
 7. A method for producinga core paper comprising the steps of: providing a material suspensionwith at least one proportion of a reconstituted fiber material mixtureand a wet sealer as a first additive, preferably from a stockpreparation process; adding an active substance active on a boundarysurface as a second additive in said finished stock suspension in theconstant part of a paper production process; producing a core paper fromsaid material suspension on a paper machine, in particular on aFourdrinier wire, in particular with a vibrating screen, and with orwithout a dandy roll in particular with an attached hybrid former and aweb guide through a calender.
 8. The method of claim 7 wherein saidstock preparation process comprises at least one method step selectedfrom a group comprising screening of a fiber material, in particular,with multi-stage slot-pressure-screening, a cleaner system process,dispersing stages, ash removal processes, combinations thereof and thelike.
 9. The method of claim 7 further comprising the additional stepof: impregnating said core paper with synthetic resin, whereinimpregnation is in particular resinification, saturation and/or resinimpregnation for the production of particle, in particular, fibercomposite material.
 10. The method of claim 7 further comprising theadditional step of: forming a stack made of core paper using pressureand temperature to produce laminated material.
 11. A core paper whichwas produced according to the method according to claim
 7. 12. The useof the core paper according to claim 1 as a material component incomposite materials, in particular in laminate materials, compactboards, fiber composites, particle composites and interpenetratingcomposites.
 13. The use of the core paper according to claim 1 ascarrier material for a web-shaped layer structure and in particular foroverlays, decorative paper, films and nonwoven materials and/or as acover layer, in particular as an overlay and pre-impregnated paperand/or as a carrier material on carrier boards in particular of woodfiberboards, such as chip boards, oriented strand boards (OSB),fiberboards of high or medium density, plywood, mineral-bonded woodmaterials on a plastic base, solid wood panels, countertops, floorcovering, and preferably for the production of fiber compositematerials, such as natural fiber reinforced plastics, wood-plasticcomposites and fiber-ceramic composites, and/or in return thereof, inparticular as regenerated paper for coating back sides such as inparticular for laminates, surface-coated boards such as woodfiberboards, panels, and combinations thereof and the like.